The two main plots in To Kill a Mockingbird concern the mysterious and unseen Boo Radley, and the children's attempts to get a glimpse of him (Part One); and the trial of Tom Robinson (Part Two). Author Harper Lee ties the two plots together at the end of the story when Boo Radley finally makes his first appearance, coming to Jem's and Scout's rescue when Bob Ewell--Tom Robinson's accuser--tries to kill them.